1. Field of the Disclosure
The present disclosure relates to the technical field of nuclear medicine imaging, and in particular to a multi-layer staggered coupling collimator, a radiator, a detection device and a scanning apparatus.
2. Discussion of the Background Art
A Single Photon Emission Computed Tomograph (abbreviated as SPECT hereinafter) is an advanced nuclear medicine molecular imaging tool, which can obtain metabolism information on an organism in a noninvasive manner, and play a major role in mechanism study, diagnosis and treatment of critical diseases such as a cardiovascular system disease, a nervous system disease and tumor. The SPECT includes a probe, a rotatable rack, a scanning table, and an image acquisition and processing workstation, where the probe generally includes a scintillator detector and a collimator. In imaging, drugs with radioactive nuclides such as Tc-99m are injected into a human body, and the probe is arranged around the human body to acquire gamma rays from different angles so as to obtain two dimensional radioactive intensity distribution maps from different angles. Then, a three dimensional image that reflects radioactive drug distribution of the human body is obtained by image reconstruction.
A spatial resolution, sensitivity and an imaging field of view are three most important performance indexes of the SPECT. The spatial resolution reflects a capability of the SPECT to distinguish details of an object, and improvement of the spatial resolution can increase richness and definition of details of the acquired image. The sensitivity reflects a capability of the SPECT to detect an object with a low activity, and improvement of the sensitivity can reduce an injection amount of the radioactive drug or imaging time. The imaging field of view reflects a range of sizes of objects which can be scanned by the SPECT, and improvement of the SPECT can accelerate or optimize scanning on a big object. Improvement of one or more of the indexes is a foundational direction of development of the SPECT over years.
The performance of the collimator is one of the main factors influencing the performance of the SPECT system. Optimizing the design of the collimator is an important way to improve the performance of the SPECT system. The collimator is generally a square plate in which through-holes are arranged densely. The plate is generally made of a heavy metal such as lead and tungsten or an alloy thereof, which can block gamma photons that do not fly in holes and allow gamma photons flying through the holes. A linear track of flight of gamma photons can be determined based on the direction of the holes on the collimator and positions on the detector radiated by the gamma photons obtained by the scintillator detector. Performances of the collimator are generally also indicated by the spatial resolution, the sensitivity and the field of view and the like, and the performance indexes are determined by geometric parameters (such as a size of the plate, a shape, a size and a deepness of a hole), a material and a machining precision of the collimator. The indexes are in a mutual constraint relation, that is, increase of one index normally results in decrease of another index. Generally, a suitable combination of performances is selected by performing optimization according to an application demand.
Presently, for imaging of a big animal or a person, the resolution and the sensitivity of the SPECT system needs to be improved greatly. Compared with a positron emission computed tomography which is also a nuclear medicine molecular imaging tool, the SPECT system has a lower resolution and an even lower sensitivity by two orders of magnitude. The low sensitivity and resolution limit the capability of the SPECT system (particularly a clinic SPECT system based on a parallel hole collimator) to diagnose diseases early, find and analyze a lesion quantitatively, and reflect details of an object accurately. Therefore, designing a high performance collimator is still effective means to improve the performances of the SPECT system.
In actual imaging with the clinic SPECT, collimators with different performances may be selected according to application conditions. For this reason, it needs to dismount an old collimator and install a new collimator. Since the collimator is big and heavy, it is not convenient to replace the collimator, and damages may occur during the replacing process. In addition, an SPECT system is normally configured with a very small number of collimators with different performances, and therefore a range of selection is small, which means there may not be sufficient options of collimators to be selected for different applications. An ideal solution to this problem is to design a multiple-performance collimator having adjustable performances.
Processing difficulty is also a main factor to be considered in designing the collimator, and a collimator with an extreme performance or a collimator with complex functions may be impossible due to processing difficulty. Therefore, it needs to consider processing difficulty of the collimator when designing the collimator, in addition to functions of the collimator.
Therefore, it is desired to provide a multi-layer staggered coupling collimator with an improved structure, a radiator, a detection device and a scanning apparatus, so as to solve the problems in the conventional technology.